Scientists with the National Oceanic and Atmospheric Administration have predicted a slightly calmer season than normal but acknowledged much of the outlook depends on El Nino nuances they do not yet completely understand.

“There is still much to learn,” said Robert Detrick, director of NOAA’s Office of Oceanic and Atmospheric Research, “like why some storms become large and dangerous hurricanes and some do not”.

At a news conference in Miami, NOAA released its official predictions for the hurricane season, which begins June 1.

• Nine to 15 named storms, with sustained winds of at least 39 mph;

• Of those, four to eight are likely will become hurricanes, with winds of at least 74 mph;

• Of those, one to three will become major hurricanes of Category Three, Four or Five, with winds greater than 111 mph.

Dr Detrick said that every year, predictions improve because of advances in technology.

But he added that predicting storms does have some uncertainty, with the unknown El Nino factor looming in the fall.

The El Nino phenomenon includes warm water over a vast area of the tropical Pacific Ocean which creates conditions in the atmosphere that inhibits hurricanes in the Atlantic.

Winds blowing from the west disrupt those storms that try to form and the storms that do form tend to get blown apart by the wind shear.

Dr Detrick said NOAA has improved its ability to predict rapid strengthening and weakening of storms, along with better reliability in forecasting hurricane paths up to seven days out.

But predicting where hurricanes go and how dangerous they can be remains guesswork to some extent.

Technology is improving, which has kept the NOAA predictions over recent years at about 70 per cent correct, he said.

Forecasts of the past four years have been pretty much on the money, thanks to more improved data-gathering methods.

This year, NOAA will make greater use of airborne drones that are designed to take measurements of temperatures and wind direction and speed and other data over the Atlantic, beginning in September.

Team effort

Hurricane season begins on June 1, though Tropical Storm Alberto formed two weeks ago along the Mid-Atlantic coastline.

That doesn’t indicate a more active season, Dr Detrick said.

Last year, NOAA came close with its prediction of 12 to 18 named storms, of which six to 10 were expected to become hurricanes, including three to six major hurricanes.

The actual tally: Nineteen tropical storms, with seven growing into hurricanes, four of which were major hurricanes.

It was an above-average number of tropical storms with a near-normal number of major hurricanes.

Coastal residents should take precautions, and now is the time to make emergency plans, said Timothy Manning, deputy administrator for the Federal Emergency Management Agency’s Office of Protection and National Preparedness.

“Emergency management is a team effort and the most important members of that team is the public,” he said.

“The time to prepare is now. It just takes one storm to come ashore... to create a disaster.”

Gerry Bell, lead hurricane season forecaster with NOAA’s Climate Prediction Center, said this year’s predictions, in part, are based on past years with similar climate patterns.

“It’s a little less than what we’ve seen,” he said, “but, that’s still a lot of activity”. “It doesn’t mean anybody's off the hook at all and now’s the time to start preparing for this hurricane season.”